Antimalarial activities and toxicity levels of selected medicinal plants used in Kenya

Abstract

Background: Resistance development to antimalarial drugs necessitates the look at traditional medicinal plants as sources of novel compounds that could have the otential to be developed into new antimalarial therapies. Four medicinal plants used in Kenya to treat malaria were investigated.

Objective: To determine the in vitro and in vivo antimalarial activity and safety of four medicinal plants used in Kenya to treat malaria.

Materials and Methods: Ximenia americana, Sericocomopsis hilderbrandtii, Pentas lanceolata and Fuerstia africana were collected from their habitat, dried, and extracted with methanol and aqueous solvents. In vitro antiplasmodial activity carried out using Plasmodium falciparum, In vivo antimalarial activity using Plasmodium berghei ANKA strain in Swiss albino mice. Cytotoxicity was carried out using MTT assay on VeroE99 cell lines, acute toxicity was investigated in Swiss albino mice.

Results: All extracts had good in vitro activity against D6 strain of Plasmodium falciparum with IC₅₀<20µg/ml.  Aerial parts of Fuerstia africana methanol extract had the highest in vitro activity.  Seven extracts showed good in vivo activity with chemosuppresion >30% while three demonstrated low activity. Fuerstia africana was moderately cytotoxic. Except for Ximenia americana water extract, all the extracts were safe with LD₅₀ > 5000mg/Kg.

Conclusion: Results of this study support medicinal use of these plants and indicate that useful compounds can be isolated for further exploitation, formulation and use.

Keywords: Medicinal plants, antiplasmodial activity, cytotoxicity, acute toxicity